1. Technical Field
The present disclosure relates to an optical image collecting system. More particularly, the present invention relates to a miniaturized optical image collecting system applicable to electronic products.
2. Description of Related Art
In recent years, with the popularity of mobile products with camera functionalities, a demand for miniaturized optical system is increasing. A photosensitive sensor of a conventional optical system is typically a CCD (Charge-Coupled Device) or a CMOS (Complementary Metal-Oxide-Semiconductor) sensor. As the advanced semiconductor manufacturing technologies have allowed the pixel size of sensors to be reduced and the optical systems have gradually evolved toward a field of higher megapixels, there is an increasing demand for better image quality.
A conventional optical system employed in a portable electronic product, as shown in the U.S. Pat. Nos. 7,869,142 and 8,000,031, mainly adopts a structure of four lens elements or five lens elements. Due to the popularity of mobile products with high-end specifications, such as smart phones Tablet PC and PDAs (Personal Digital Assistants), requirements of higher megapixels and better image quality have increased rapidly. However, the conventional optical systems cannot satisfy the requirements of high-end optical systems with camera functionalities.
A conventional optical system with six lens elements, as shown in US publication No. 2012/0243108, is favorable for improving resolving power. However, the refractive power of the fifth lens element tends to result in excessive aberrations which are not favorable for correction. Besides, the optical system lacks a meniscus lens element having a concave object-side surface so that it is not favorable for correcting astigmatism and off-axis aberration. It is also not favorable for the responding efficiency of an image sensor so as to influence image quality.
Since the miniaturized optical system with high resolving power applicable to electronic products has become a trend, an optical system with short total track length and high image quality is needed. Therefore, it is favorable for avoiding the excessive refractive power which results into aberration, it is favorable for reducing the angle of incidence onto the image sensor from the off-axis field, and it is also favorable for the image sensor fully receiving the lights from objects so as to improve image quality.